Field of the Invention
This invention relates to a cooling element, and in particular to a cooling element for multiple electric devices which has a fluid channel arrangement providing a pulsating heat pipe behavior.
Description of Prior Art
Previously there is known a cooling element with a flow channel having a meandering shape comprising a plurality of parallel fluid channel sections which are interconnected with loops. An evaporator receives heat from electric components and passes the heat to the fluid channel. A condenser cools fluid received from the evaporator via the fluid channel.
During operation a temperature gradient prevails between the evaporator and the condenser, causing unstable pressure conditions. Heat passed to the fluid by the evaporator causes bubbles in the fluid channel sections to grow continuously. This pushes the fluid column in the fluid channel sections toward the condenser. Simultaneously, the cooling at the condenser further enhances the pressure difference between the opposite ends of the cooling element. In this way the unstable pressure conditions are formed.
Due to the loops interconnecting the fluid channel sections the motion of fluid slugs and vapor bubbles in one fluid channel section also leads to motion of slugs and bubbles in the next fluid channel section towards the evaporator (high-temperature). The inter-play between the driving force and the restoring force leads to oscillation of the vapor bubbles and fluid slugs.
A problem with the above described cooling element is that practical tests have shown that the temperature distribution at different parts of the evaporator is uneven.